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Title: Fermi-LAT observations of the 2014 May-July outburst from 3C 454.3

We observed a prominent outburst of the flat spectrum radio quasar 3C 454.3 in 2014 June with the Fermi Large Area Telescope. This outburst was characterized by a three-stage light-curve pattern—plateau, flare, and post-flare—that occurred from 2014 May to July, in a similar pattern as observed during the exceptional outburst in 2010 November. The highest flux of the outburst reported in this paper occurred during 2014 June 7–29, showing a multiple-peak structure in the light-curves. The average flux in these 22 days was found to be $$F[E\gt 100\,\mathrm{MeV}]=(7.2\pm 0.2)\times {10}^{-6}$$ ph cm -2 s -1, with a spectral index, for a simple power law, of $${\rm{\Gamma }}=2.04\pm 0.01$$. That made this outburst the first γ-ray high state of 3C 454.3 ever to be detected by Fermi with such a hard spectrum over several days. The highest flux was recorded on 2014 June 15, in a 3 hr bin, at MJD 56823.5625, at a level of $$F[E\gt 100\,\mathrm{MeV}]=(17.6\pm 1.9)\times {10}^{-6}$$ ph cm -2 s -1. Furthermore, the rise time of one of the short subflares was found to be $${T}_{r}=1200\pm 700$$ s at MJD = 56827, when the flux increased from 4 to 12 × 10 -6 ph cm -2 s -1. Finally, we collected several photons above 20 GeV during this outburst, including one at 45 GeV on MJD 56827, constraining the γ-ray emission region to be located close to the outer boundary of the broad-line region, leading to fast flux variability.
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [1] ;  [4]
  1. Univ. of Johannesburg (South Africa). Dept. of Physics
  2. Stanford Univ., CA (United States). W.W. Hansen Experimental Physics Lab.
  3. Univ. of Bordeaux (France). Centre of Nuclear Studies of Bordeaux-Gradignan
  4. National Inst. of Nuclear Physics, Padova (Italy); Univ. of Padov (Italy). Dept. of Physics
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 830; Journal Issue: 2; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; gamma rays: galaxies; quasars: individual (3C 454.3)
OSTI Identifier: